Team Galactic Headquarters is Team Galactic's third hideout located in Veilstone City. The Galactic Key is required to open the doors found throughout the entire Galactic Headquarters. After completing the Snowpoint Gym talking to the player's rival at Lake Acuity, the player can obtain a Galactic Key a Galactic Grunt dropped to access the building.
Team Galactic's HQ is the most open and easiest to find out of all the main game antagonists' HQ's.
Team Rockets was under the Celadon City Game Corner, Team Magma/Aqua was in a seacave just north of Lilycove City, Team Plasma was in an underground castle surrounding the Pokemon League.